From Slab to Tabletop

How one craftsman took a big chunk of tree and turned it into furniture. January 27, 2007

I have a slab cut from the base of a large oak tree, about 4" thick and about 4' in diameter, that I'd like to make a rough table out of. Nothing fancy, really, but I would like to preserve the color of the wood.

I really don't know the first thing about this kind of woodworking and was hoping someone could give me a list of general steps I need to take to make this lumber suitable for use. Is kiln drying necessary? What do I need to treat the wood with to preserve its color and prevent rotting? I will probably use it outdoors, so if it takes a while to dry, that's no problem.

Forum Responses
(Sawing and Drying Forum)
From contributor O:
The first thing you should know is that it will split when it dries. I have overcome this by sawing the slab in half, then rejoining the halves after they have completed drying. The edges will have to be jointed to make them straight. It should dry relatively fast through the end grain. As for the finish, I have never seen any wood exposed to the weather that lasted long. If it is dried inside away from the sun and rain, the color should stay.

From contributor M:
Thanks for the quick response! Yeah, I figured it would split, but won't the two pieces still split after I saw it in half? Also, sorry for the rookie question, but when you say the edges have to be jointed... I'm not sure what that means - just trimming them down to line them up? I'll keep it in the garage to dry - no problem. But after it's dry, do I just apply some sort of weather seal to preserve it?

From contributor D:
It will dry and crack, but so what. I've been messing around with this kind of thing using slab wood and half logs to make benches and stair treads for outside. Casual rustic stuff. I can't put this through my planer, so I've been just belt sanding the saw marks out (start at 50 grit, then 80, then 120). I use a draw knife to get the bark off. I leave the edges "live." For a finish I mix 1 part SPAR varnish, 2 parts linseed oil, 2 parts mineral spirits. I put on at least three coats to start. Then slap it on once in the fall and once in the spring. Takes 5 minutes. I find that the older, moldy, spalted, even blackened stuff still looks interesting. Here's a related Knowledge Base article:

A Finish for Outdoor Furniture

From contributor B:
I think I have already invented your wheel. I started with a live oak slab 42"x52" that had 4 trunks grown together. It was from a fresh cut tree and quite wet. I did not want it to dry fast, as the faster it dries, the more it will crack. My thinking was to seal it as best I could to slow the drying. In theory, if it dries slow enough, it will not crack. (I am safe with that statement because if it ever cracks, then "it dried too fast.") Good logic...? I put 3 coats of epoxy on all surfaces and sealed the moisture in. Nothing can seal it perfectly and it will eventually dry and may crack. If so, it goes back to the bench when fully cured/cracked and the cracks will be refilled with epoxy, the slab stripped down and then oiled/polyurethaned as the final finish.

I slabbed it 3 1/2" thick with my chainsaw (Stihl 084 with 52" bar on a Logosol mill) and put it on my workbench, attached a fence board on each side of it that just cleared the highest protrusion of the slab, laid two 3/4" x 8" pieces of plywood across the fence boards so that they were a couple of inches apart. I then set my router up with a 1 1/8" flat bottom bit with the depth set to take off the highest 1/8th of the slab by sliding the router along the crack between the two pieces of plywood. Lower the bit 1/8" more and repeat - keep repeating until the bit has flattened the whole slab. Turn the slab and repeat the process. I then sanded to 220 grit, wiped with denatured alcohol to dry so the epoxy would adhere better and coated with 3 coats of Mas Epoxy. I was told I had a better chance of the Mas epoxy not clouding from the moisture in the wood. I found an old feed store dolly and made it into a table base. It has been in my living room since June of 2004. It has not cracked a bit. When the light is just right, I can see what appears to be millions of tiny crinkles in the epoxy, which I take to be from the slab shrinking. I cannot feel them nor see them without the right light angle.

Slab on my shop bench with 2 coats epoxy - be sure to put at least a 4 mil sheet of plastic on your bench under the slab before epoxying or you will have a new top for your bench. The cloudy area at the bottom is due to light reflection. I stuffed more bark into the voids in the bark inclusions before filling with epoxy. I also taped the underside of all cracks/holes that might allow epoxy to run through - and a lot did.

From the original questioner:
Contributor B, that's exactly what I'm trying to do here - thanks so much for taking the time to describe the process and include your pics. I hope my table ends up looking anywhere near that good!